2000/08/18 by Q. Daniel Wang, Wang, Q. Daniel
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0008303
6 pages (including figures), an invited talk presented in the conference, Galaxy Disks and Disk Galaxies
arxiv created 2000/08/18 · arxiv updated 2009/12/01
I review recent results from our deep ROSAT and Chandra observations of two galaxies, M101 and NGC 4631, in fields of exceptionally low Galactic extinction. Large amounts of X-ray-emitting gas are detected in these galaxies. Such gas is produced primarily in massive star forming regions and have an average characteristic temperature of a few times 106 K. Cooler gas (∼ 106 K) is found typically outside galactic disks and may represent outflows from blown-out superbubbles. Propagation of star formation, driven by the expansion of hot gas, appears to be operating in giant HII complexes. A substantial fraction of photo-evaporated gas in such complexes may be mass-loaded into hot gas, which explains their large X-ray luminosities. These processes likely play an important role in determining the global properties of the interstellar medium, especially the disk/halo interaction.